I currently have a HP Media Center M7470n as my desktop computer. I know it's a little dated and isn't meant to run high end games but I was told I can get Starcraft 2 to run on high/ultra if I were to upgrade to the right graphics card. The person told me that installing a GeForce 9600GT/9800 or ATI 4650 would give it enough power to run the game with no problems or lag. I decided to do a little more research to find out whether it's true or not but from what I've seen so far, neither video card can run SC2 on high. Currently my M7470n is all stock besides the ram being upgraded to 4GB but I'm willing to upgrade the PSU and video card so I can enjoy SC2 to the fullest. Thank you for your time and responses!
have you got a budget? it mostly depends on your resolution and what settings you are willing to play at (by the sounds of it you want max settings).
Your current Mobos best upgrade would be an Athlon 64 4800+ which wouldn't be worth the cost, and dont invest in cards such as the 'GeForce 9600GT/9800 or ATI 4650' they are two generations old.
this sounds like a bit of a mobo/ram/gpu/PSU upgrade here, the best ram you could have now is DDR 400Mhz 4GB ram... and while that PCI-E 1.0 slot won't affect graphics performance (in real world performance), i would reccommend a large upgrade.